Author: Singru R.
Publisher: Springer Publishing Company
ISSN: 0959-3993
Source: World Journal of Microbiology and Biotechnology, Vol.19, Iss.4, 2003-06, pp. : 387-390
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Abstract
Sclerospora graminicola is an obligate parasite of its natural host pearl millet, Pennisetum glaucum and causes economic losses of the crop in semi-arid regions of Asia and Africa. The pathogen is capable of infecting a previously resistant host as it evolves rapidly to new virulent forms, a characteristic of retrotransposon activation. Retrotransposons are mobile repeat elements, and are known to mutate the organism's genes on activation by abiotic and biotic stress factors. We screened the λgt11 genomic library of the Path-6 isolate of S. graminicola with P5 retroelement, which belongs to the copia-like retrotransposon family. The library clones, designated as SgP5-1, SgP5-2, SgP5-3 and SgP5-4 were found to be distributed invariantly among genomes of five host-genotype-specific downy mildew pathotypes. At the RNA level, an amplified expression of P5-like sequences and an additional band of size 1.8 kb were found in compatible host–pathogen interaction but not in the incompatible system. This finding indicates that the fungus may be actively expressing the P5-like sequences in the host and the element is suppressed in a resistant host. Such an evidence for the role of retroelements in pearl millet-downy mildew interaction is being proposed for the first time.
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